Two-Step Curing of Semiconductor Polymer Layers
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Solution Overview
Problem
Conventional polymer curing processes for semiconductor devices, such as those using PBO layers, are slow and inefficient, leading to prolonged cure cycles that can deform via sidewalls and increase packaging size, contrary to the goal of miniaturization.
Innovation Solution
A method involving crosslinking the polymer surface using UV radiation followed by rapid thermal curing with techniques like conduction, convection, infrared, or microwave heating, achieving complete curing within 60 minutes with temperatures above 200°C and maintaining steep via wall profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional slow curing processes are used, then the polymer layer can be cured without deforming via sidewalls, but the curing time is prolonged and packaging size increases
Solution Approach 1:
The curing process is divided into two distinct stages: a first curing stage that maintains steep via sidewall profiles, and a second curing stage that completes the polymerization. This segmentation allows each stage to be optimized for its specific function, resolving the contradiction between maintaining precision and reducing time.
Solution Approach 2:
The first curing stage performs preliminary curing action that establishes the via sidewall profiles before the second curing stage completes the process. By performing the profile-maintaining action first, the patent prevents sidewall deformation while enabling faster overall curing.
2Reliability
If conventional curing processes are used, then the polymer layer can be cured, but the packaging size increases contrary to miniaturization goals
Solution Approach 1:
The two-stage curing process segments the curing function, allowing the first stage to achieve sufficient curing while maintaining compact dimensions, and the second stage to complete the curing. This enables reduced packaging size while maintaining curing reliability.
Solution Approach 2:
The patent changes curing parameters between stages: the first stage uses conditions optimized for profile maintenance with shorter duration, while the second stage uses conditions optimized for complete curing. This parameter optimization enables smaller packaging while ensuring thorough curing.
3Loss of time
If rapid thermal curing is applied directly, then curing time is reduced, but via sidewall profiles become deformed
Solution Approach 1:
The first curing stage performs preliminary curing that establishes stable via sidewall profiles before rapid thermal curing is applied in the second stage. This preliminary action prevents deformation during the rapid curing phase.
Solution Approach 2:
The curing process is segmented into a first stage that maintains precision and a second stage that provides rapid curing. This segmentation allows rapid thermal curing to be applied without deforming sidewalls, as the structure is already stabilized by the first stage.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach allows for faster processing times, maintaining steep via wall profiles, and achieving desirable mechanical properties like tensile strength and elongation, thus supporting the production of smaller, more compact semiconductor devices.
Implementation Method 1
crosslinking a surface of the polymer layer, for example, by subjecting the polymer layer to an ultraviolet (UV) bake
Implementation Method 2
thermally curing the polymer layer in a second process... by using at least one thermal process selected from the group consisting of conduction, convection, infrared, and microwave heating
Implementation Method 3
thermally curing the polymer layer in a second process... by using at least one thermal process selected from the group consisting of conduction, convection, infrared, and microwave heating
Implementation Method 4
thermally curing the polymer layer in a second process... by using at least one thermal process selected from the group consisting of conduction, convection, infrared, and microwave heating
Implementation Method 5
thermally curing the polymer layer in a second process... by using at least one thermal process selected from the group consisting of conduction, convection, infrared, and microwave heating
Data Source
AI summary
A semiconductor device and method of making the semiconductor device is described. A semiconductor die is provided. A polymer layer is formed over the semiconductor die. A via is formed in the polymer layer. The polymer layer is crosslinked in a first process. The polymer layer is thermally cured in a second process. The polymer layer can comprise polybenzoxazoles (PBO), polyimide, benzocyclobutene (BCB), or siloxane-based polymers. A surface of the polymer layer can be crosslinked by a UV bake to control a slope of the via during subsequent curing. The second process can further comprise thermally curing the polymer layer using conduction, convection, infrared, or microwave heating. The polymer layer can be thermally cured by increasing a temperature of the polymer at a rate greater than or equal to 10 degrees Celsius per minute, and can be completely cured in less than or equal to 60 minutes.